[khanar]

A 45 year old woman has been on a long car trip and she had no access to drinking water. She came to the ER with dizziness and confusion. Examination noted severe postural hypotension. Her husbands stated that she used to drink 25 diet coke bottles per day and she goes to the bathroom several times per day. Even during the car trip she had to urinate behind the tree three times. Urine glucose dipstick test was negative and urine osmolalilty was very low.
What could be the cause of this woman's condition?

A- Psychogenic polydipsia
B- Compulsive water drinking
C- Diabetes insipidus
D- Diabetes mellitus
E- Soda toxicity

 

[mosallam]

i think it is case of diabetes insipedus

 

[snoureldine]

the answer is A

a typical case of psychogenic polydepsia... a patient being deprived from a water source her body has been used to, leading to signs of dehydration and hypernatremia.

another way this can show up... is the same patient wo drinks that 25 cans of diet coke a day.. was admitted to the hospital for some other reason ( broken femur) and shows signs of dehydration and hypernatremia. because she was deprived of that intake at the hospital.

 

[snoureldine]

regarding DI

i think it is case of diabetes insipedus

DI starts at an earlier age( childhood or early Adult life) unless it is secondary to neoplastic, infiltrative lesions, radiotherapy, encephalitis, TB, syphilis, meningitis.... etc
if that was the case.. there should be a history of something

 

[khanar]

Answer is DI

the correct answer is DI
This lady wouldn't continue to pee if it was psychogenic polydipsia.
As pointed out by snoureldine it could be an acquired form of DI for example she has a pituitary adenoma causing central DI

 

[snoureldine]

the correct answer is DI
This lady wouldn't continue to pee if it was psychogenic polydipsia.
As pointed out by snoureldine it could be an acquired form of DI for example she has a pituitary adenoma causing central DI

i believe u might be mistaken... i had the same scenario but as i pointed she was admitted to the hospital i was working in for a broken femur and showed signs of confusion and hypernatremina.. and the diagnosis was Psychogenic polydipsia.
I AM CONFUSED...

 

[rasheed]

Two identical options are wrong

Psychogenic polydipsia and compulsive water drinking are two names for the same condition.
If you have two similar or identical options they must be both wrong.
See this article
http://www.usmle-forums.com/usmle-articles/1928-two-similar-options-wrong.html

 

[khanar]

Here's how ...

DI starts at an earlier age( childhood or early Adult life) unless it is secondary to neoplastic, infiltrative lesions, radiotherapy, encephalitis, TB, syphilis, meningitis.... etc
if that was the case.. there should be a history of something

Don't be confused.
In psychogenic polydipsia (PP) the problem is too much drinking (cause) causing too much urination (effect) while in DI it's the reverse, where too much urination (cause) results in too much drinking (effect).
This lady used to drink a lot to compensate her polyuria, if it was PP then she should stop urinating because u removed the cause (though she may start to have irritability and all kinds of psychic stuff because she's not used to stop drinking which is the question that you have seen before).

The fact that she continued to urinate dilute urine means practically she has u undergone a diagnostic "water deprivation test" by the long trip

In water deprivation test, PP patients will be able to concentrate their urine while DI patients will not.

The question could have been more difficult if they ask whether its central or nephrogenic DI but they did not do it because there's nothing in the vignette that points to either of them.